1. Field of the Invention
An aspect of the present invention relates in general to an optical pickup actuator and an optical recording and/or reproducing apparatus, and, more specifically, to an optical pickup actuator which drives an objective lens to record and/or reproduce information onto and/or from an optical information storage medium, and an optical recording and/or reproducing apparatus having the same installed therein.
2. Description of the Related Art
An optical recording and/or reproducing apparatus is provided with an optical pickup to record optical information by irradiating a laser beam onto an optical recording medium, such as a compact disk (CD), a digital versatile disk (DVD), etc., and reproducing the recorded optical information from the optical recording medium.
The optical pickup requires an objective lens, which focuses an incident light to the optical recording medium, and an actuator, which drives the objective lens in a focusing direction and a tracking direction.
The actuator includes a base, a lens holder on which an objective lens is mounted, and a magnetic circuit to drive the lens holder in a focusing direction and a tracking direction, while supporting the lens holder to move with respect to the base.
The magnetic circuit comprising focusing coils driving an objective lens in a focusing direction, tracking coils driving an objective lens in a tracking direction, and magnets installed, facing the coils to interact with the coils. The actuator drives the focusing coils and the tracking coils independently to control the movement of the objective lens in the focusing direction and the tracking direction.
In recent years, attention has been focused on developing and establishing the standard of DVDs holding a large amount of data (greater than 4.7 GB per side) and HD (High Definition)—DVDs characterized of higher density and capable of recording high definition moving images (greater than 23 GB per side). In the cases of these high-density optical recording media, the thickness of an optical recording medium needs to be reduced as the NA (numerical aperture) of an objective lens is increased. For instance, although the thickness of a conventional CD is 1.2 mm and the thickness of a conventional DVD is 0.6 mm, a next generation HD-DVD may be as thin as 0.1 mm.
However, as the rotation speed of the operated recording medium increases, the high-density, thin optical recording medium generates problems of eccentricity due to manufacturing errors that may be present. As a result, the optical recording medium does not rotate horizontally, but, rather, may be deformed up and down.
Since focusing control and tracking control of an objective lens in corresponding directions are not sufficient to accurately focus a light to a recording side of an optical disk, there is a need to develop an actuator, which is capable of performing focusing, tracking and tilting control on the objective lens, while maintaining a high sensitivity.